Subtilase SprP exerts pleiotropic effects inPseudomonas aeruginosa

Alexander Pelzer,Michael Bott,Frank Rosenau,Susanne Wilhelm,Horst Funken,Tino Polen,Karl‐Erich Jaeger

doi:10.1002/mbo3.150

Abstract

The open reading frame PA1242 in the genome of Pseudomonas aeruginosa PAO1 encodes a putative protease belonging to the peptidase S8 family of subtilases. The respective enzyme termed SprP consists of an N-terminal signal peptide and a so-called S8 domain linked by a domain of unknown function (DUF). Presumably, this DUF domain defines a discrete class of Pseudomonas proteins as homologous domains can be identified almost exclusively in proteins of the genus Pseudomonas. The sprP gene was expressed in Escherichia coli and proteolytic activity was demonstrated. A P. aeruginosa ΔsprP mutant was constructed and its gene expression pattern compared to the wild-type strain by genome microarray analysis revealing altered expression levels of 218 genes. Apparently, SprP is involved in regulation of a variety of different cellular processes in P. aeruginosa including pyoverdine synthesis, denitrification, the formation of cell aggregates, and of biofilms.

Highlights

Pseudomonas aeruginosa is an opportunistic aerobic Gramnegative bacterium regarded as the major cause of death in cystic fibrosis patients (Murray et al 2007)
These proteases were further analyzed for conserved domains (Marchler-Bauer et al 2011) and orf PA1242 was identified to encode a putative protease previously annotated as a hypothetical protein in the Pseudomonas Genome Database (Winsor et al 2011)
The newly identified protein harbors an N-terminal type I export signal peptide of 21 aa followed by a 233 aa domain without any similarity to known proteins which was qualified as domain of unknown function (DUF)

Summary

Introduction

Pseudomonas aeruginosa is an opportunistic aerobic Gramnegative bacterium regarded as the major cause of death in cystic fibrosis patients (Murray et al 2007). P. aeruginosa Protease SprP lipopolysaccharides, and several secreted factors (Ramphal and Pier 1985; Nicas and Iglewski 1986; Drake and Montie 1988; Sato et al 1988; Gupta et al 1994) All these virulence factors are regulated by several complex regulatory systems including the quorum sensing (QS) system (Pesci et al 1999; Venturi 2006). Proteases represent a very diverse group of hydrolases which are found in all kingdoms of life (Rawlings and Barrett 1994) In bacteria, they are often involved in essential regulatory processes, for example, via degradation of abnormally folded proteins or by controlling the intracellular amounts of sigma factors and chaperones (Gottesman 1996). We have demonstrated that SprP exhibits protease activity and further report on the role of SprP for various important cellular functions in P. aeruginosa including growth, cellular motility, biofilm formation, and pyoverdine production

Experimental Procedures

Results

Discussion